Feed correction mechanism



July 5, 1960 H. E. BALSIGER FEED CORRECTION MECHANISM Filed May 2, 1957 INVENTOR HAROLD 541.51:

TTORNEY FEED CORRECTION MECHANISM Harold E. Balsiger, Waynesboro, Pa., assignor to Landis Tool Company, Waynesboro, Pa.

Filed May 2, 1957, Ser. No. 656,530

5 Claims. (Cl. 51-165) This invention relates to a feed mechanism for a grinding machine, particularly a feed mechanism of the type which may be mechanical such as a pawl and ratchet mechanism or which may be hydraulic in which a feed piston receives intermittent impulses of fluid under pressure. 7

Because of the friction between guide surfaces, it is difiicult to provide an apparatus or device which will move a wheel support accurately one-half thousandth of an inch, and this type of feed mechanism has never been depended upon to effect uniform or accurate increments of feed. Since one ten-thousandth of an inch has taken the place of five ten-thousandths of an inch and automatically operated machines must hold accurate size without the attention of an operator, it has become necessary to provide a device to effect accurate adjustments of feed of one half of one ten-thousandth of an inch or less. Friction between guide surfaces resists such small increments. The principal obstacle so far as friction is concerned is starting friction which is much greater than running friction. In order to be able to make such small increments, it is necessary to eliminate all friction or to effect adjustments under circumstances which give the effect of zero friction. 7

'It is an object of this invention to provide a feed mechanism for grinding machines in which starting friction is substantially eliminated.

Another object is to provide means for advancing or retracting a grinding wheel by increments such as onehalf of one ten-thousandth of an inch.

Another object is to provide means for effecting a positioning movement of the grinding wheel and for timing the feed adjustment to occur simultaneously with said positioning movement.

Another object is to provide means for measuring a finished workpiece and for actuating said feed adjusting means in accordance with the result of said measuring operation.

Another object is to provide a switch for effecting said feed adjustment at a predetermined point in the positioning movement.

The a drawing is a combined hydraulic and electric diagram.

The drawing shows a wheel mounting comprising a wheel base 10 slidably mounted on a slide member 11 which, in turn, is mounted on a bed (not shown). A grinding wheel 12 is rotatably supported on said wheel base 10 for grinding a workpiece W. The means for moving said grinding wheel 12 toward and from said workpiece is shown in detail in Patent 2,313,479, granted March 9, 1943, and consists of a feed screw which may be moved endwise by a piston 21 in cylinder 22. Said feed screw 20 engages a worm wheel 25 in the lower end of a vertical feed shaft 26. A worm wheel 27 on the upper end of said feed shaft 26 is connected through suitable gearing including a worm gear on the nited St t s stem ice end of hand wheel shaft 28. Hand wheel shaft 28 may be manually actuated by hand wheel 29 to rotatefshaft 26 and with worm wheel 25 acting as a pinion and feed screw 20 serving as a rack, to advance the wheel base 10 along said feed screw 20. It may also be adjusted by a pawl and ratchet mechanism including a ratchet wheel 35. A pawl 36 on piston 37 in cylinder 38 serves to rotate ratchet wheel and hand wheel shaft 28 in a clockwise direction. A pawl 40 on piston 41 in cylinder 42 engages ratchet wheel 35 to causerotation of said Wheel 35 in a counter-clockwise direction. Cylinders 38 and 42 are moved to the right by fluid under pressure against the reset springs 39 and 43 respectively. A limit switch 50 mounted on slide member 11 having a contact 51 may be actuated by a dog 52 suitably positioned on wheel base 10.

Operation After a workpiece W has been ground, it is passed through a gauge consisting of a passage 60 into which is inserted a feeler 61 to engage workpieces W as they pass by. Said feeler 61 is part of limit switch 62 having contacts 63 and 64.

If a workpiece W or a predetermined number of workpieces are oversized, contact 63 will be closed and in turn will close a relay contact 2K-1 in a circuit which includes normally open control relay contact 26CR1, normally closed control relay contact 28CR2 and control relay 27CR. An unground workpiece is placed in the machine and fluid under pressure is applied to piston 21 in cylinder 22 to move the wheel base 10 rapidly toward workpiece W. At a predetermined point in this movement, dog 52 will close contact 51 of switch 50 to complete a circuit to energize control relay 26CR. Control relay contact 26CR1 will then complete a circuit through contact ZK-l and control relay contact 28CR2 to energize control relay 27CR. Control relay contacts 27CR1 and 27CR4 will complete a circuit to energize valve solenoid P which shifts valve, 70 to the right and directs fluid from pump P through throttle valve to cylinder 38 shifting piston 37 and pawl 36 to the right. Said pawl 36 actuates ratchet wheel 35 in a clockwise direction to advance grinding wheel 12 by increments suflicient to correct the oversize condition of the workpiece.

If -a workpiece or a predetermined number of workpieces are undersized, the gauge switch will close contact 64 and complete a circuit to close contact lK-l. As described above, the circuit is completed when the wheel base 10 advances for the grinding operation and limit switch 50 is actuated to energize control relay 26CR closing control relay contact 26CR1. Contact lK-l completes a circuit through control relay contact 27CR3 to energize control relay 280R. Control relay contacts 28CR1 and 2SCR3 complete a circuit to energize valve solenoid G which shifts valve 70 to the left and directs fluid through throttle valve to cylinder 42, shifting piston 41 and pawl 40 to the right. Pawl 40 rotates ratchet wheel 35 and shaft 28 in a counter-clockwise direction to back off the grinding wheel 12 by the amount of undersize in the previously ground workpiece.

When the wheel base 16 is retracted after grinding each workpiece, switch 5% is opened and control relay 260R deenergized. Whichever valve solenoid has been actuated is also deenergized and valve '70 is returned to center position in which both cylinders 33 and 42 are connected with exhaust. When so connected, the springs 39 and 43 move respective pistons 37 and 41 to the left to reset them for the feed increment. By actuating ratchet wheel 35 while the wheel base 19 is in motion, there is no inertia or starting friction to overcome and small increments of adjustment of the wheel base 10 can be made accurately in either direction.

I claim:

1. In a grinding machine, a grinding wheel support, a grinding wheel rotatably mounted thereon, mechanism for feedingsaid grinding wheelctoward and from operative position including a feed screw, means for effecting a continuous feeding movement of. said feed screw and said grinding wheel, adjusting means for actuating said feed mechanism in either direction, a gauge for measuring workpieces after they have been ground, said gauge having means for providing a signal in accordance with variations of workpieces from the desired size, mean operable in response to the signal to adjust said feed mechanism in accordance with the condition of the Work as reflected by the signal, and means operable during said continuous feeding movement for actuating said adjusting means to correct the setting of the feed mechanism for the next piece to be ground.

2. In a grinding machine, a grinding wheel support, a grinding wheel'rotatably mounted thereon, mechanism for feeding said grinding wheel toward and from operative position including a'feed screw, means for effecting a continuous feeding movement of said feed screw and said grinding wheel, adjusting means for actuating said feed mechanism in either direction, a gauge for measuring workpieces after they have been ground, means for providing a signal in accordance with variations of workpieces from the desired size, means operable in response to the signal to adjust said feed mechanism in accordance with the condition of the work as reflected by the signal, and means operable during said continuous feeding movement for actuating said adjusting means to correct the setting of the feed mechanism for the next piece to be ground.

3. In a grinding machine, a grinding wheel support, a grinding wheel rotatably mounted thereon, mechanism for feedingsaid grinding wheel toward and from operative position including a feed screw, means for effecting a continuous feeding movement of said feed screw and said grinding wheel, adjusting means for actuating said feed mechanism in either direction, means for providing a signal in accordance with variations of workpieces from the desired size, means operable in response to the signal to adjust said feed mechanism in accordance with the condition of the work as reflected by the signal, and

means operable during said continuous feeding movement for actuating said adjusting means to correct the setting of the feed mechanism for the next piece to be ground.

4. In a grinding machine, a grinding wheel support, a grinding wheel rotatably mounted thereon, mechanism for feeding said grinding wheel toward and from operative position including a-feed screw, means for effecting a continuous feeding movement of said feed screw and said grinding wheel, adjusting means for actuating said feed mechanism in either direction, a gauge for measuring workpieces, means for providing a signal in accordance with variations of workpieces from the desired size, means operable in response'to the signal to adjust said feed mechanism in accordance with the condition of the work as reflected by the signal, and means operable during said continuous feeding movement for actuating said adjusting means to correct the setting of the feed mechanism for the next piece to be ground.

5. In a grinding machine, a grinding wheel support, a grinding wheel rotatably mounted on said grinding wheel support, mechanism for feeding said grinding wheel support, means for effecting a continuous relative transverse movement of said grinding wheel support and said grinding wheel toward and from operative position, adjusting means for actuating said feed mechanism in either direction, a gauge for measuring workpieces after they have been ground, said gauge having means for providing a signal in accordance with variation of workpieces from the desired size, means operable during said continuous transverse movement in either direction, in response to said signal to actuate said feed mechanism adjusting means to change the setting of the feed mechanism for the next piece to be ground.

References Cited in the file of this patent UNITED STATES PATENTS 1,301,377 Bruner Apr. 22, 1919 2,150,749 Price et a1. Mar. 14, 1939 2,313,479 Price et al. Mar. 9, 1943 2,692,457 Bindszus Oct. 26, 1954 

